There are four seasons on Mars and about 144 million square kilometers of surface land — almost exactly the same amount that the Earth has above sea level. The planet tilts at an angle of around 23 degrees, like the Earth, and its days are 24 hours and 40 minutes long.

As he ticks off these facts, Brown University geological sciences professor John Mustard pauses and breaks into the soft, eerie wail of a familiar TV theme song. “It’s kind of like a Twilight Zone episode,” he says. The show was famous for placing its characters in familiar situations where a certain element in the environment was askew. Mars is kind of like that. “It’s like Earth, it’s just a little off,” he says.

Mustard would know. While, of course, he hasn’t been to the Red Planet (no human has), in January of 2013, when NASA appointed a “Science Definition Team” to brainstorm objectives for their Mars 2020 rover mission, Mustard was named the chair.

“The successful landing of the Curiosity science rover on August 6, 2012 was the latest in a series of technological and scientific triumphs of NASA’s Mars Exploration Program,” begins the report that the team — which included scientists from Princeton University, the Carnegie Institute in Washington, and NASA’s Jet Propulsion Laboratory — released in July. “The prime focus of the exploration of Mars in the coming decade is to assess if life is or was present on Mars.”

The report sat on a desk on a recent afternoon in Mustard’s office on the first floor of Brown’s Lincoln Field Building. That building — a nondescript brick structure overlooking a grassy quad, just a few minutes’ walk from the bookstores and hookah lounges of Thayer Street — is perhaps the closest thing Providence has to a portal to outer space. On the second floor is the NASA-affiliated Northeast Planetary Data Center: a repository of maps; photographs; documents from NASA missions with names like Magellan, Viking 2, and Lunar Orbiter IV; and stacks of other extraterrestrial browsing material, all of it free and open to the public. On the first floor, through a hallway lined with “MARS OR BUST” bumper stickers and blown-up images of the surfaces of planets, is the room where Professor Mustard contemplates Earth’s curious next door neighbor.

The Phoenix chatted with him there recently while he awaits an announcement from NASA, in response to his team’s report, soliciting proposals for the scientific instruments that will equip the Mars 2020 rover. The announcement is expected to come later this month, Mustard says.

Our conversation has been edited and condensed.

I THINK THE TWO MOST PRESSING QUESTIONS MOST PEOPLE HAVE ABOUT MARS ARE: WILL HUMANS GO THERE? AND, IF SO, WHEN? There’s a really strong drive to have people go to Mars. And that could be in the next 15 years, something might happen. That’s an optimistic number. Or it might not happen.

And the fascinating thing is: will it be national governments that do that? Or will it be the private sector? Ten years ago I would have scoffed at the private sector, maybe even two years ago. But I think [tech billionaire and space enthusiast/entrepreneur] Elon Musk has shown enough chutzpah to actually commercialize that part of it. And, you know, maybe there’s something there. Maybe they could do it cheaper.

[NASA is] really kind of sketchy about what they’re doing with their human flight. I’d say that’s a big deal problem with NASA at the moment: what are you doing with your human flight? You sent people to the moon in the ’60s and you haven’t really sent anyone anywhere since. You’ve had a space station and then you had a shuttle program and you retired it. Can you actually launch humans into orbit? No, actually the Russians do that. What are you doing?

IS THE U.S. STILL THE WORLD POWER OF SPACE EXPLORATION? The US is the world’s foremost space-faring nation, but many nations are catching up in one area or another. Right now the US does more in more areas than anyone. But there are niche areas or targeted areas where the rest of the world has made huge strides forward. For example, it used to be that the US and Russia were the only countries who could send spacecraft to other planets. Russia, in the ’90s, pretty much pulled back from space exploration — couldn’t afford it. But Europe [the European Space Agency, which includes 20 participating nations] has since demonstrated that it can launch spacecraft to other planets and get into orbit. And just a couple years ago, India launched a spacecraft to the moon [that] went into orbit, spent a couple years there, and actually got some really high-quality data.

WHAT WILL THE MARS 2020 MISSION DO THAT THE CURRENT CURIOSITY ROVER ISN’T DOING? First of all, it’s going to collect rocks that we can bring home.

Why would be bother doing that? Because we want to answer the question, “Does life exist elsewhere in the solar system or in the universe?” We want to start in the solar system [and] Mars is the first place I can think of to go, because it’s been an Earth-like planet, it’s had all the right ingredients . . . for life to have gotten started and evolve, and we want to go see if the signs of life are left in any way shape or form.

I, personally, do not believe that there is viable life on the surface of Mars today. Some people do; I don’t. I think we’re going to be looking for the geologic record. We’re going to be looking for the fossil life.

In [this report are] our recommendations to what NASA should do for that. So what you want to do is send a rover that can do fundamental science. It’ll be like the Curiosity rover — basically the same chassis — but we would instrument it differently and we would ask it to do something different as the core [mission]. And that core is to collect rock samples . . . and fill a cache — a collection, a canister — with about 30 of these and get it ready to bring home. So we collect it and then prepare this package for return by a future spacecraft.

You look skeptical.

I’M NOT SKEPTICAL. IT’S INTERESTING. BUT IT’S A PLAN THAT I WOULDN’T SAY IS “DANGLING,” BUT . . . . There’s no closure. Right. And I think that’s the really important initial perception. It’s like, “Great! You made a cache. What are you going to do with it? Are you going to return it?”

And this gets into the complications to do science this big. I mean, this would be a $1.5 billion mission. To build the spacecraft, to launch it, to put it on the surface of Mars for a year, and to create the cache would be about $1.5 billion.